Double sleeve endoscope

ABSTRACT

Endoscopic apparatus, including a probe ( 9 ) having an anterior component ( 12 ) and a posterior component ( 14 ), and a flexible dual-sleeved tube ( 31 ). The flexible dual-sleeved tube consists of a flexible external sleeve ( 26 ) and a flexible internal sleeve ( 36 ) within the external sleeve. The sleeves are coupled between the anterior component and the posterior component so as to define an enclosure ( 37 ) between the sleeves, which enclosure is inflated in order to propel the anterior component within a lumen ( 49 ).

FIELD OF THE INVENTION

The present invention relates generally to propulsion of objects withinlumens, and specifically to methods and devices for propelling medicalinstruments through the colon.

BACKGROUND OF THE INVENTION

The use of an endoscope for examining a body cavity is well known in theart. The diagnostic and therapeutic advantages conferred by directexamination of the gastrointestinal tract with a flexible endoscope havemade this method a standard procedure of modern medicine. One of themost common endoscopic procedures is colonoscopy, which is performed fora wide variety of purposes, including diagnosis of cancer, determinationof the source of gastrointestinal bleeding, viewing a site affected byinflammatory bowel disease, removing polyps, and reducing volvulus andintussusception.

While colonoscopy is useful and effective, it is a difficult procedurefor a physician to perform and is painful and occasionally dangerous forthe patient. These problems stem from the need to push and steer thelong, flexible colonoscope through the intestine by pushing it in fromits proximal end, outside the body.

It would be desirable to provide a propulsion mechanism to push or pullthe endoscope forward from its distal end, inside the body. A number ofmethods and devices have been proposed for this purpose, although nonehas achieved clinical or commercial acceptance.

U.S. Pat. No. 4,207,872 to Meiri et al., whose disclosure isincorporated herein by reference, describes a device and method foradvancing an endoscope through a body passage utilizing multiplefluid-filled flexible protrusions distributed along an outer surface ofa sleeve containing the endoscope. Alternately increasing and decreasingthe fluid pressure within the protrusions advances the endoscope along abody passage. Each protrusion is in direct contact with an inner surfaceof the body passage and applies local contact pressure against thisrelatively small contact surface in order to propel the endoscopeforward.

U.S. Pat. No. 3,895,637 to Choy, whose disclosure is incorporated hereinby reference, describes a device able to move through a tubular organ bysequentially inflating and deflating first and second radiallyinflatable members. The inflation anchors the inflated member against alocal region of the tubular organ, while air pressure in alongitudinally inflatable communicating part of the device moves thenon-anchored part of the device longitudinally through the tubularorgan. Sufficient contact pressure of the inflated member against arelatively small length of the tubular organ is required in order forthe device to be able to progress through the organ. U.S. Pat. No.3,895,637 has no provision to distribute the contact pressure over alarger area of the tissue against which it presses in order to generatelongitudinal motion.

U.S. Pat. No. 4,321,915 to Leighton et al., whose disclosure isincorporated herein by reference, describes an everting tube device forintroducing a tool into a body cavity using alternating steps ofapplying positive pressure to evert the tube and advance the tool, andapplying a vacuum to pull the everted tube away from the tool so that anoperator can retract the tool one half of the distance it advanced inthe previous step. The operator using this device is required tomanually withdraw the tool the prescribed distance during every pressurecycle in order to avoid causing the tool to advance too far beyond thetip of the everted tube.

U.S. Pat. No. 4,403,985 to Boretos, whose disclosure is incorporatedherein by reference, describes a jet-propelled device for insertion intobody passageways. Pressurized fluid is passed to the device from outsideof the body and then ejected from an orifice in the device in onedirection in order to propel the device in the opposite direction. Thedevice of U.S. Pat. No. 4,403,985 thus generates propulsion by expellingmaterial into the body passageway.

PCT patent application PCT/IL97/00077, to Lerner, whose disclosure isincorporated herein by reference, describes an endoscopic insertiondevice in the form of a flexible tubular semi-toroidal sheath. Anendoscopic probe is inserted into the sheath, and the sheath is insertedinto a lumen. Pushing on the probe causes the sheath and the probe tomove into the lumen, by the sheath moving in the same way as the tracksof a tracked vehicle.

SUMMARY OF THE INVENTION

It is an object of some aspects of the present invention to provide animproved system and method for propelling an object within a lumen.

It is a further object of some aspects of the present invention toprovide an improved propulsion mechanism for advancing an endoscopewithin a body cavity of a patient for purposes of examination,diagnosis, and treatment.

In preferred embodiments of the present invention, a section of anendoscopic probe is advanced through the lower gastrointestinal tract ofa patient by inflation of a flexible dual-sleeved tube comprised in theprobe. The tube comprises an external sleeve and an internal sleeve, andinflation of the tube is accomplished by inflating the space between thesleeves. Prior to inflation, the internal sleeve is stored in a compact,folded or rolled-up state, inside a stationary posterior component ofthe probe. The posterior component is typically coupled to a hand helddevice at or adjacent to the patient's anus. The external sleeve is alsostored in a folded or rolled up state, inside an anterior component ofthe probe.

As the tube is inflated, preferably using a pressurized gas, theanterior component is propelled forward, and the dual-sleeved tube isgradually fed out between the anterior and posterior components. Duringthis process, the portion of the external sleeve that has been fed outexpands radially outward to contact the intestinal wall. This portion ofthe external sleeve remains substantially stationary relative to theintestinal wall while the tube is inflated. Longitudinal motion of theexternal sleeve relative to the wall generally occurs only in the regionof the anterior component itself. The anterior component thus advanceseasily, and trauma to the gastrointestinal tract is minimized.

The internal sleeve feeds out at the same time as the external sleeve.The interior of the portion of the internal sleeve that has been fed outforms a passageway through which cables and tubes linking the anteriorand posterior components are pulled forward by the motion of theanterior component. During motion of the anterior component there isvirtually no relative motion between the cables and tubes and theinternal sleeve, since both are pulled forward at substantially the samerate. Preferably, the cables carry video signals from a camera head inthe anterior component to a display coupled to the posterior component,while the tubes enable endoscopic equipment or material to be passed inor out between the anus and the anterior component.

In preferred embodiments of the present invention, the head of theanterior component comprises a transparent viewing window. The windowenables imaging devices, such as a miniature video camera and/or a lightsource, as are known in the art, to capture endoscopic images. Means foroperating the imaging devices, such as wires and/or fiber-optic lines,pass through the internal sleeve and so do not contact the externalsleeve of the tube.

To remove the probe, the space between the sleeves is deflated and thetube is pulled out through the anus.

Advancing the probe through the gastrointestinal tract by inflating thedual-sleeved tube reduces or eliminates the necessity of applyingmechanical force at the proximal end of the probe (outside the patient'sbody) in order to insert the probe, as is required using conventionalendoscopes. The present invention thus reduces or eliminates thenecessity of applying concentrated, local pressure to any part thepatient's body, reduces or eliminates rubbing and friction between theprobe or parts of it and the patient's body, and avoids ejecting fluidsor other materials into the body passageway. Furthermore, thedual-sleeved tube reduces or eliminates damage or trauma to the externalsleeve or to the colon wall by insulating movement of endoscopicequipment from the external sleeve.

There is therefore provided, according to a preferred embodiment of thepresent invention, endoscopic apparatus, including:

a probe including an anterior component and a posterior component; and

a flexible dual-sleeved tube, including a flexible external sleeve and aflexible internal sleeve within the external sleeve, coupled between theanterior component and the posterior component so as to define anenclosure between the sleeves, which enclosure is inflated in order topropel the anterior component within a lumen.

Preferably, the apparatus includes an imaging device inserted within theanterior component which captures an image of the lumen.

Further preferably, the apparatus includes a handle which removablymates with the posterior component so as to enable an operator to holdthe posterior component in a generally stationary position.

Preferably, the internal sleeve includes a passageway for conveyingendoscopic equipment between the anterior and posterior components.

Preferably, the apparatus includes at least one tube fixedly connectedto the anterior component and residing within the internal sleeve.

Preferably, the at least one tube is substantially stationary relativeto a section of the internal sleeve.

Further preferably, a section of the external sleeve is substantiallystationary relative to a wall of the lumen.

Preferably, the anterior component includes an anterior-componentchamber, and the dual-sleeved tube includes an anterior-componentportion which is held in a compact state within the anterior-componentchamber and which feeds out from a proximal end of the anteriorcomponent as the anterior component is propelled within the lumen.

Preferably, the anterior component includes a head section and aflexible sleeve coupling the anterior-component chamber to the headsection, which sleeve enables the head section to be oriented.

Further preferably, the dual-sleeved tube inlcudes a posterior-componentportion which is held in a compact state coupled to the posteriorcomponent and which feeds out from a distal end of the posteriorcomponent as the anterior component is propelled within the lumen.

Preferably, the enclosure is a gas-tight enclosure which is inflated bya fluid in order to propel the anterior component within the lumen.

Preferably, the fluid is an inert gas.

Alternatively, the fluid is an inert liquid.

There is further provided, according to a preferred embodiment of thepresent invention, a method for propelling an endoscopic probe componentwithin a lumen, including:

providing an anterior and a posterior component of the probe;

coupling between the anterior component and the posterior component adual-sleeved tube including a flexible external sleeve and a flexibleinternal sleeve within the external sleeve, so as to define an enclosurebetween the sleeves; and

inflating the enclosure to advance the anterior component through thelumen.

Preferably, inflating the enclosure includes inflating the enclosuresuch that a section of the external sleeve remains substantiallystationary relative to a wall of the lumen as the anterior componentadvances.

Preferably, the method includes coupling one or more tubes to theanterior component, and inflating the enclosure includes maintaining theone or more tubes substantially stationary relative to the internalsleeve as the anterior component advances.

Preferably, providing the anterior component includes providing ananterior-component chamber within the anterior component, and couplingthe dual-sleeved tube includes storing a portion of the tube in theanterior-component chamber.

Preferably, coupling the dual-sleeved tube includes storing a portion ofthe tube in the posterior component.

Preferably, the method includes imaging a section of the lumen with acamera assembly coupled to the anterior component.

Further preferably, the method includes removably mating the posteriorcomponent with a handle so as to enable an operator to hold theposterior component in a generally stationary position.

The present invention will be more fully understood from the followingdetailed description of the preferred embodiments thereof, takentogether with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, sectional drawing of an outer section of anendoscopic probe, according to a preferred embodiment of the presentinvention;

FIG. 2 is a schematic sectional drawing of a camera assembly comprisedin the endoscopic probe of FIG. 1, according to a preferred embodimentof the present invention;

FIG. 3 is a schematic sectional drawing of the endoscopic probe of FIG.1 in an assembled form, according to a preferred embodiment of thepresent invention; and

FIG. 4 is a schematic sectional drawing of an alternative endoscopicprobe, according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a schematic sectional drawingof an outer section 10 of an endoscopic probe 9, according to apreferred embodiment of the present invention. Section 10 comprises ananterior component 12, which is propelled forward into a lumen or otherpassage 49, and a posterior component 14 which remains in asubstantially stationary position outside lumen 49. Typically lumen 49is the colon of a patient, and probe 9 is use to perform an endoscopicprocedure, as described further hereinbelow. Components 12 and 14 aregenerally circular in cross-section.

Anterior component 12 comprises a cylindrical head 16, closed at itsdistal end by a transparent viewing window 18. Head 16 comprises arecess 17 at the proximal side of window 18, within which recess acamera of a camera assembly 50 may be positioned. Camera assembly 50 isdescribed hereinbelow with reference to FIG. 2, and for clarity assembly50 is not shown in detail in FIG. 1. Assembly 50 and recess 17 areconstructed so that the assembly mates with the recess. Anteriorcomponent 12 comprises one or more openings 19, to which respective oneor more tubes 13 are fixedly attached, so that respective passages areformed by the tubes to the distal side of head 16.

Anterior component 12 further comprises a semi-rigid sleeve 20. Sleeve20 is fixedly attached between the proximal end of head 16 and thedistal end of a tube-holder 23 comprised in component 12. Tube-holder 23comprises an outer cap 22 having an internal flange 29 at its distalend, which flange is fixedly attached to an inner spindle 24. Spindle 24comprises an external protrusion 21 close to its proximal end, theprotrusion having an external radius less than the internal radius ofcap 22, so that a circular slot 30 is formed between the flange and thecap. Also, a cylindrical chamber 28 is formed between cap 22 and spindle24.

Posterior component 14 comprises a spindle 32 having an external flange27 at its proximal end. Spindle 32 and inner spindle 24 are implementedto have substantially similar internal radii. Spindle 32 comprises anexternal protrusion 33 at its distal end. A vent 42 is formed in flange27.

Section 10 further comprises a dual-sleeved tube 31. Tube 31 comprises aflexible external sleeve 26 and, within the external sleeve, a flexibleinternal sleeve 36. The proximal end of sleeve 26 is fixedly attached toan external surface of flange 27, preferably by an O-ring 57, so as toform a gas-tight seal at end 25. The distal end of sleeve 26 is fixedlyattached, preferably by an O-ring 55 gripping spindle 24, to theproximal side of flange 29, within chamber 28, so as to form a gas-tightseal. Prior to using section 10, a distal section of external sleeve 26is stored in a folded or rolled-up compact state in anterior componentchamber 28.

The distal end of internal sleeve 36 is fixedly attached to the proximalside of protrusion 21 of anterior component 12, at an internal edge 35of spindle 24, so as to form a gas-tight seal. The proximal end ofsleeve 36 is fixedly attached to the distal side of flange 27, so as toform a gas-tight seal. Preferably, the gas-tight seals at the distal andproximal ends of sleeve 36 are formed by an O-ring 53 and an O-ring 51respectively. In some preferred embodiments of the present invention,some or all of O-rings 57, 55, 53, and 51, are replaced and/orsupplemented by other sealing devices known in the art, such as glue.Prior to using section 10, a proximal section of internal sleeve 36 isstored in a folded or rolled-up compact state over spindle 32, on theproximal side of protrusion 33.

It will be appreciated that dual-sleeved tube 31 couples anteriorcomponent 12 to posterior component 14, and that an enclosure 37 formedbetween the sleeves of tube 31 is a gas-tight enclosure.

In order to propel component 12 into lumen 49, enclosure 37 is inflatedvia vent 42 with an inert gas such carbon dioxide. Alternativelyenclosure 37 is inflated with an inert liquid such as sterile water. Theinflation of enclosure 37 causes the compacted sections of both theinternal and external sleeves to unfold and feed out over protrusion 33and from slot 30 respectively. Thus tube 31 increases in length, and ifcomponent 14 is maintained substantially stationary outside lumen 49,typically close to a patient's anus 48, component 12 is propelled intothe lumen.

As enclosure 37 is inflated, component 12 moves within lumen 49, pullingthe one or more tubes 13 attached to component 12 within the lumen.During the process of inflation, a portion 44 of sleeve 26, formed byexternal sleeve 26 feeding out from chamber 28, expands radially and maycontact the wall of lumen 49. However, portion 44 remains substantiallyfixed in a longitudinal direction, since sleeve 26 is fixedly attachedto posterior component 14. Thus rubbing and trauma to the wall of thelumen are minimized.

Similarly, a portion 46 of sleeve 36, formed by internal sleeve 36feeding out over protrusion 33, moves radially inward during theinflation process. Since internal sleeve 36 is fixedly attached toanterior component 12, the sleeve moves longitudinally at substantiallythe same rate as component 12. Thus, there is substantially no relativemotion between the one or more tubes 13 and internal sleeve 36, so thatthe risk of potential damage due to motion between the tubes and theinternal sleeve is substantially reduced.

As enclosure 37 is inflated, a passageway 47, connecting anteriorcomponent 12 to posterior component 14, is formed within internal sleeve36.

FIG. 2 is a schematic sectional drawing of a camera assembly 50comprised in endoscopic probe 9, according to a preferred embodiment ofthe present invention. Before inserting the probe into lumen 49,assembly 50 is inserted into passageway 47, as shown in more detail inFIG. 3 below. The camera assembly is used for generating images fromwithin the lumen. Assembly 50 preferably comprises a charge coupleddevice (CCD) camera 52, which is fixedly mounted to a spring 58 at thespring's distal end. Spring 58 is fixedly connected at its proximal endto the distal end of a semi-rigid, generally cylindrical guide 54.

CCD camera 52 preferably comprises a CCD array 64, on which an image ofthe lumen wall is formed by an objective 62. CCD array 64 and objective62 are mounted in a housing 72, the outer surface of which is formed soas to mate with recess 17. Housing 72 comprises a transparent window 70via which light is projected to illuminate the lumen and via whichobjective 62 receives the light. Lamps 60, mounted within housing 72,are used to generate the light needed. Lamps 60 and CCD array 64 arepowered by wires 66 which are fed through a wire shield 68 and pass outthrough the proximal end of guide 54. In addition to being held byspring 58, camera 52 is fixedly attached to a plurality of rigid wires56, which slideably feed though cylindrical channels in guide 54 to theproximal end of guide 54. Guide 54 also comprises open-sided channelswhich are able to accommodate the one or more tubes 13, as described inmore detail below with respect to FIG. 3.

FIG. 3 is a schematic sectional drawing of endoscopic probe 9 in anassembled form, according to a preferred embodiment of the presentinvention. In FIG. 3 probe 9 is assumed to be used in an investigationof a gastrointestinal tract 82 of a patient, although it will beunderstood that the probe can be used to investigate other lumens orpassages. Prior to inflation of enclosure 37, assembly 50 is insertedinto outer section 10. Posterior component 14 of section 10 is theninserted into a mating section 86 of a handle 80, and is fixedly heldtherein by the handle. Section 86 has an opening 84 which mates withvent 42, so that inflation of enclosure 37 is accomplished via opening84. Also prior to inflation, tubes 13 and wires 66 in shield 68 are fedthrough an open central portion 88 of posterior component 14 and throughan open proximal end 90 of mating section 86. Wires 66 are connected toa video monitor (not shown) for imaging the inside of tract 82.

As enclosure 37 is inflated, anterior component 12 moves through tract82 as described above, and the one or more tubes 13 and wire shield 68are pulled along with component 12 and assembly 50 into the tract.Preferably tubes 13 are used, inter alia, for the purposes of irrigationor evacuation from tract 82. Wires 56 are manipulated to orient camera52 in different directions, as required by an operator, causing sleeve20 to flex accordingly. The proximal ends of wires 56 exit to handle 80,enabling the operator to manipulate the wires using suitable controls inorder to orient camera 52. Once camera 52 is correctly oriented, the oneor more tubes 13 may be used to transfer endoscopic equipment, such as abiopsy probe, to the distal side of anterior component 12 and so to asite imaged by the camera. It will be appreciated that while enclosure37 is inflated, motion of objects such as assembly 50 or probes withintubes 13 is insulated from tract 82 by double-sleeved tube 31, so thatdiscomfort to the patient is minimized.

To remove endoscope 9 from tract 82, assembly 50 is withdrawn viapassageway 47. Enclosure 37 is then deflated, and anterior component 12is withdrawn from tract 82 by pulling on the one or more tubes 13.

FIG. 4 is a schematic sectional drawing of an alternative endoscopicprobe 92, according to a preferred embodiment of the present invention.Apart from the differences described below, the operation of probe 92 isgenerally similar to that of probe 9 (FIG. 1), so that elementsindicated by the same reference numerals in both probes 9 and 92 aregenerally identical in construction and in operation. In probe 92, head16 and semi-rigid sleeve 20 are not implemented. A sealed endoscopiccamera 94, preferably coupled by wires 96 passing through passageway 47and posterior component 14 to an external monitor, is positioned on thedistal side of flange 29. Most preferably, camera 94 has an outsidediameter smaller than the outside diameter of cap 22, and an insidediameter greater than the inside diameter of spindle 24. In this case,as enclosure 37 is inflated, anterior component 12 moves into lumen 49and pushes camera 94 ahead of itself.

It will be appreciated that preferred embodiments of the presentinvention are implemented so that components contacting walls of alumen, or having a possibility of contacting a biologically sensitiveregion, are formed from biocompatible materials such as inert plastic orstainless steel. In some preferred embodiments of the present invention,a plurality of sections 10 are implemented in a disposable, non-reusableform, so that after one section 10 has been used it is discarded andreplaced. For example, in probe 9 the more costly assembly 50 withcamera 52 can be reused without the need for sterilization, since it isentirely protected from contact with the patient's body by section 10.

Although preferred embodiments of the present invention are describedhereinabove with reference to moving an endoscopic probe through a bodylumen, it will be understood that the novel principles of the presentinvention may be used to move objects in lumens and other regions fornon-medical applications. An example of a non-medical applicationincludes examination within a highly corrosive or high-temperatureenvironment, where it is not desirable to have moving parts of apropulsion unit or an instrument package exposed to the environment. Itwill be appreciated that for non-medical applications such as theexample herein, some or all of probe 9 is implemented from materialssubstantially inert to the environment wherein the probe is operated. Itis also to be understood that the propulsion unit and instrument packagein the example above can be powered by batteries and can store dataand/or transmit data by wireless communications, as is known in the art.

PCT patent application PCT/IL00/00017, which is assigned to the assigneeof the present patent application, and whose disclosure is incorporatedherein by reference, describes an endoscopic probe that is propelled ina lumen by a single inflatable sleeve, rather than a dual sleeve asdescribed herein. Certain features of the probe described in this PCTapplication may be implemented, mutatis mutandis, in the dual-sleevedevice of the present invention.

It will thus be appreciated that the preferred embodiments describedabove are cited by way of example, and that the present invention is notlimited to what has been particularly shown and described hereinabove.Rather, the scope of the present invention includes both combinationsand subcombinations of the various features described hereinabove, aswell as variations and modifications thereof which would occur topersons skilled in the art upon reading the foregoing description andwhich are not disclosed in the prior art.

1. Endoscopic apparatus, comprising: a probe comprising an anteriorcomponent and a posterior component; and a flexible dual-sleeved tube,comprising a flexible external sleeve and a separate flexible internalsleeve disposed within the external sleeve, the flexible dual-sleevedtube being coupled between the anterior component and the posteriorcomponent so as to define an enclosure between the sleeves, whichenclosure is inflated in order to propel the anterior component within alumen, and at least one tube fixedly connected to the anterior componentand residing within the internal sleeve.
 2. Apparatus according to claim1, and comprising an imaging device inserted within the anteriorcomponent which captures an image of the lumen.
 3. Apparatus accordingto claim 1, and comprising a handle which removably mates with theposterior component so as to enable an operator to hold the posteriorcomponent in a generally stationary position.
 4. Apparatus according toclaim 1, wherein the internal sleeve comprises a passageway forconveying endoscopic equipment between the anterior and posteriorcomponents.
 5. Apparatus according to claim 1, wherein the at least onetube is substantially stationary relative to a section of the internalsleeve.
 6. Apparatus according to claim 1, wherein the external sleevehas one end connected to the anterior component and an opposite endconnected to the posterior component.
 7. Endoscopic apparatus,comprising: a probe comprising an anterior component and a posteriorcomponent; and a flexible dual-sleeved tube, comprising a flexibleexternal sleeve and a separate flexible internal sleeve disposed withinthe external sleeve, the flexible dual-sleeved tube being coupledbetween the anterior component and the posterior component so as todefine an enclosure between the sleeves, which enclosure is inflated inorder to propel the anterior component within a lumen, and wherein asection of the external sleeve is substantially stationary relative to awall of the lumen.
 8. Endoscopic apparatus, comprising: a probecomprising an anterior component and a posterior component; and aflexible dual-sleeved tube, comprising a flexible external sleeve and aseparate flexible internal sleeve disposed within the external sleeve,the flexible dual-sleeved tube being coupled between the anteriorcomponent and the posterior component so as to define an enclosurebetween the sleeves, which enclosure is inflated in order to propel theanterior component within a lumen, and wherein the anterior componentcomprises an anterior-component chamber, and wherein the dual-sleevedtube comprises an anterior-component portion which is held in a compactstate within the anterior-component chamber and which feeds out from aproximal end of the anterior component as the anterior component ispropelled within the lumen.
 9. Apparatus according to claim 8, whereinthe anterior component comprises a head section and a flexible sleevecoupling the anterior-component chamber to the head section, whichsleeve enables the head section to be oriented.
 10. Endoscopicapparatus, comprising: a probe comprising an anterior component and aposterior component; and a flexible dual-sleeved tube, comprising aflexible external sleeve and a separate flexible internal sleevedisposed within the external sleeve, the flexible dual-sleeved tubebeing coupled between the anterior component and the posterior componentso as to define an enclosure between the sleeves, which enclosure isinflated in order to propel the anterior component within a lumen, andwherein the dual-sleeved tube comprises a posterior-component portionwhich is held in a compact state coupled to the posterior component andwhich feeds out from a distal end of the posterior component as theanterior component is propelled within the lumen.
 11. Endoscopicapparatus, comprising: a probe comprising an anterior component and aposterior component; and a flexible dual-sleeved tube, comprising aflexible external sleeve and a separate flexible internal sleevedisposed within the external sleeve, the flexible dual-sleeved tubebeing coupled between the anterior component and the posterior componentso as to define an enclosure between the sleeves, which enclosure isinflated in order to propel the anterior component within a lumen, andwherein the enclosure is a gas-tight enclosure which is inflated by afluid in order to propel the anterior component within the lumen. 12.Apparatus according to claim 11, wherein the fluid is an inert gas. 13.Apparatus according to claim 11, wherein the fluid is an inert liquid.14. A method for propelling an endoscopic probe component within alumen, comprising the steps of: providing an anterior and a posteriorcomponent of the probe; coupling between the anterior component and theposterior component a dual-sleeved tube; forming said dual-sleeved tubeas a flexible external sleeve and a separate flexible internal sleevewithin the external sleeve so as to define an enclosure between thesleeves; and inflating the enclosure to advance the anterior componentthrough the lumen, and coupling one or more tubes to the anteriorcomponent, and wherein inflating the enclosure comprises maintaining theone or more tubes substantially stationary relative to the internalsleeve as the anterior component advances.
 15. A method for propellingan endoscopic probe component within a lumen, comprising the steps of:providing an anterior and a posterior component of the probe; couplingbetween the anterior component and the posterior component adual-sleeved tube; forming said dual-sleeved tube as a flexible externalsleeve and a separate flexible internal sleeve within the externalsleeve so as to define an enclosure between the sleeves; and inflatingthe enclosure to advance the anterior component through the lumen.wherein said step of providing the anterior component comprisesproviding an anterior-component chamber within the anterior component,and wherein coupling the dual-sleeved tube comprises storing a portionof the tube in the anterior-component chamber.
 16. A method according toclaim 15, wherein inflating the enclosure comprises inflating theenclosure such that a section of the external sleeve remainssubstantially stationary relative to a wall of the lumen as the anteriorcomponent advances.
 17. A method for propelling an endoscopic probecomponent within a lumen, comprising the steps of: providing an anteriorand a posterior component of the probe; coupling between the anteriorcomponent and the posterior component a dual-sleeved tube; forming saiddual-sleeved tube as a flexible external sleeve and a separate flexibleinternal sleeve within the external sleeve so as to define an enclosurebetween the sleeves: and inflating the enclosure to advance the anteriorcomponent through the lumen, wherein said step of coupling thedual-sleeved tube comprises storing a portion of the tube in theposterior component.
 18. A method according to claim 17, and comprisingimaging a section of the lumen with a camera assembly coupled to theanterior component.
 19. A method according to claim 17, and comprisingremovably mating the posterior component with a handle so as to enablean operator to hold the posterior component in a generally stationaryposition.
 20. Endoscopic apparatus, comprising: a probe comprising ananterior component and a posterior component; and a flexibledual-sleeved tube, comprising a flexible external sleeve and a separateflexible internal sleeve disposed within the external sleeve, theflexible dual-sleeved tube being coupled between the anterior componentand the posterior component so as to define an enclosure between thesleeves, which enclosure is inflated in order to propel the anteriorcomponent within a lumen, and wherein the external sleeve and theinternal sleeve each has a first end connected to the anterior componentand an opposite second end connected to the posterior component, thefirst end of the external sleeve being connected to the anteriorcomponent at a different location than the first end of the internalsleeve, and the second end of the external sleeve being connected to theposterior component at a different location than the second end of theinternal sleeve.
 21. Endoscopic apparatus, comprising: a probecomprising an anterior component and a posterior component; and aflexible dual-sleeved tube, comprising a flexible external sleeve and aseparate flexible internal sleeve disposed within the external sleeve,the flexible dual-sleeved tube being coupled between the anteriorcomponent and the posterior component so as to define an enclosurebetween the sleeves, which enclosure is inflated in order to propel theanterior component within a lumen, and wherein the anterior componentcomprises a semi-rigid sleeve.